xref: /openbmc/linux/arch/ia64/lib/ip_fast_csum.S (revision 0d3b051a)
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Optmized version of the ip_fast_csum() function
4 * Used for calculating IP header checksum
5 *
6 * Return: 16bit checksum, complemented
7 *
8 * Inputs:
9 *      in0: address of buffer to checksum (char *)
10 *      in1: length of the buffer (int)
11 *
12 * Copyright (C) 2002, 2006 Intel Corp.
13 * Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com>
14 */
15
16#include <asm/asmmacro.h>
17#include <asm/export.h>
18
19/*
20 * Since we know that most likely this function is called with buf aligned
21 * on 4-byte boundary and 20 bytes in length, we can execution rather quickly
22 * versus calling generic version of do_csum, which has lots of overhead in
23 * handling various alignments and sizes.  However, due to lack of constrains
24 * put on the function input argument, cases with alignment not on 4-byte or
25 * size not equal to 20 bytes will be handled by the generic do_csum function.
26 */
27
28#define in0	r32
29#define in1	r33
30#define in2	r34
31#define in3	r35
32#define in4	r36
33#define ret0	r8
34
35GLOBAL_ENTRY(ip_fast_csum)
36	.prologue
37	.body
38	cmp.ne	p6,p7=5,in1	// size other than 20 byte?
39	and	r14=3,in0	// is it aligned on 4-byte?
40	add	r15=4,in0	// second source pointer
41	;;
42	cmp.ne.or.andcm p6,p7=r14,r0
43	;;
44(p7)	ld4	r20=[in0],8
45(p7)	ld4	r21=[r15],8
46(p6)	br.spnt	.generic
47	;;
48	ld4	r22=[in0],8
49	ld4	r23=[r15],8
50	;;
51	ld4	r24=[in0]
52	add	r20=r20,r21
53	add	r22=r22,r23
54	;;
55	add	r20=r20,r22
56	;;
57	add	r20=r20,r24
58	;;
59	shr.u	ret0=r20,16	// now need to add the carry
60	zxt2	r20=r20
61	;;
62	add	r20=ret0,r20
63	;;
64	shr.u	ret0=r20,16	// add carry again
65	zxt2	r20=r20
66	;;
67	add	r20=ret0,r20
68	;;
69	shr.u	ret0=r20,16
70	zxt2	r20=r20
71	;;
72	add	r20=ret0,r20
73	mov	r9=0xffff
74	;;
75	andcm	ret0=r9,r20
76	.restore sp		// reset frame state
77	br.ret.sptk.many b0
78	;;
79
80.generic:
81	.prologue
82	.save ar.pfs, r35
83	alloc	r35=ar.pfs,2,2,2,0
84	.save rp, r34
85	mov	r34=b0
86	.body
87	dep.z	out1=in1,2,30
88	mov	out0=in0
89	;;
90	br.call.sptk.many b0=do_csum
91	;;
92	andcm	ret0=-1,ret0
93	mov	ar.pfs=r35
94	mov	b0=r34
95	br.ret.sptk.many b0
96END(ip_fast_csum)
97EXPORT_SYMBOL(ip_fast_csum)
98
99GLOBAL_ENTRY(csum_ipv6_magic)
100	ld4	r20=[in0],4
101	ld4	r21=[in1],4
102	zxt4	in2=in2
103	;;
104	ld4	r22=[in0],4
105	ld4	r23=[in1],4
106	dep	r15=in3,in2,32,16
107	;;
108	ld4	r24=[in0],4
109	ld4	r25=[in1],4
110	mux1	r15=r15,@rev
111	add	r16=r20,r21
112	add	r17=r22,r23
113	zxt4	in4=in4
114	;;
115	ld4	r26=[in0],4
116	ld4	r27=[in1],4
117	shr.u	r15=r15,16
118	add	r18=r24,r25
119	add	r8=r16,r17
120	;;
121	add	r19=r26,r27
122	add	r8=r8,r18
123	;;
124	add	r8=r8,r19
125	add	r15=r15,in4
126	;;
127	add	r8=r8,r15
128	;;
129	shr.u	r10=r8,32	// now fold sum into short
130	zxt4	r11=r8
131	;;
132	add	r8=r10,r11
133	;;
134	shr.u	r10=r8,16	// yeah, keep it rolling
135	zxt2	r11=r8
136	;;
137	add	r8=r10,r11
138	;;
139	shr.u	r10=r8,16	// three times lucky
140	zxt2	r11=r8
141	;;
142	add	r8=r10,r11
143	mov	r9=0xffff
144	;;
145	andcm	r8=r9,r8
146	br.ret.sptk.many b0
147END(csum_ipv6_magic)
148EXPORT_SYMBOL(csum_ipv6_magic)
149